Jeepers It's the Creeper - S2-E3
Stupidity: When the gang delivers the bank guard to Mr. Carswell's (The Creeper) house, he never asks the gang for the paper just in case it might be incriminating evidence (which it very much is), and he also ties up the guard at his house while trying to get it from them later, even though the gang already tried to contact law enforcement. Why would Mr. Carswell act in such a blatantly villainous manner that puts him at risk, when it would be just more practical and safer to keep up the act?
Stupidity: The villain should've removed the tape hidden in the mask once he had it as it was incriminating evidence.
Chosen answer: A ghost wouldn't have to keep any food in the fridge - they don't need to eat. So it is one thing that proves the ghost is not a ghost.